Capacitors can be classified as, for example, metal-oxide-silicon (MOS) capacitors, PN-junction capacitors, polysilicon-insulator-polysilicon (PIP) capacitors, metal-insulator-metal (MIM) capacitors, and the like, according to their junction structures. Specifically, capacitors, other than MIM capacitors, use monocrystalline or polycrystalline silicon as at least one electrode material. The use of monocrystalline or polycrystalline silicon as an electrode material may cause a reduction in the resistance of capacitor electrodes. Moreover, when a bias voltage is applied to a monocrystalline or polycrystalline silicon electrode, a depletion region may be formed and the voltage may become unstable, which may make it difficult to maintain the capacitance at a uniform level.
Accordingly, MIM capacitors have been applied in radio frequency (RF) devices, various analog/mixed-signal devices, and the like. For example, MIM capacitors have been used as RF capacitors for high frequency circuits, analog capacitors or filters for wired/wireless communications, capacitors for image sensors, capacitors for LCD Driver ICs (LDIs), and the like.
The capacitance-versus-voltage relationship of an MIM capacitor is generally represented by a quadratic equation. It may, therefore, be desirable to maintain the voltage coefficient of capacitance (abbreviated to “VCC”), which is a quadratic coefficient in the quadratic equation, at less than a threshold value, so that an integrated circuit device having the MIM capacitor can operate in a stable manner within a predictable range. Furthermore, to attain a stable, error-free integrated circuit device, the scattering of VCC values of a plurality of MIM capacitors formed on a given wafer is typically as small as possible.